John C.S. McCaw and Enrique Cuan-Urquizo
While additive manufacturing via melt-extrusion of plastics has been around for more than several decades, its application to complex geometries has been hampered by the…
Abstract
Purpose
While additive manufacturing via melt-extrusion of plastics has been around for more than several decades, its application to complex geometries has been hampered by the discretization of parts into planar layers. This requires wasted support material and introduces anisotropic weaknesses due to poor layer-to-layer adhesion. Curved-layer manufacturing has been gaining attention recently, with increasing potential to fabricate complex, low-weight structures, such as mechanical metamaterials. This paper aims to study the fabrication and mechanical characterization of non-planar lattice structures under cyclic loading.
Design/methodology/approach
A mathematical approach to parametrize lattices onto Bèzier surfaces is validated and applied here to fabricate non-planar lattice samples via curved-layer fused deposition modeling. The lattice chirality, amplitude and unit cell size were varied, and the properties of the samples under cyclic-loading were studied experimentally.
Findings
Overall, lattices with higher auxeticity showed less energy dissipation, attributed to their bending-deformation mechanism. Additionally, bistability was eliminated with increasing auxeticity, reinforcing the conclusion of bending-dominated behavior. The analysis presented here demonstrates that mechanical metamaterial lattices such as auxetics can be explored experimentally for complex geometries where traditional methods of comparing simple geometry to end-use designs are not applicable.
Research limitations/implications
The mechanics of non-planar lattice structures fabricated using curved-layer additive manufacturing have not been studied thoroughly. Furthermore, traditional approaches do not apply due to parameterization deformations, requiring novel approaches to their study. Here the properties of such structures under cyclic-loading are studied experimentally for the first time. Applications for this type of structures can be found in areas like biomedical scaffolds and stents, sandwich-panel packaging, aerospace structures and architecture of lattice domes.
Originality/value
This work presents an experimental approach to study the mechanical properties of non-planar lattice structures via quasi-static cyclic loading, comparing variations across several lattice patterns including auxetic sinusoids, disrupted sinusoids and their equivalent-density quadratic patterns.
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Robert F. Bruner, Michael J. Innes and William J. Passer
Set in September 1992, this exercise provides teams of students the opportunity to negotiate terms of a merger between AT&T and McCaw Cellular. AT&T, one of the largest U.S…
Abstract
Set in September 1992, this exercise provides teams of students the opportunity to negotiate terms of a merger between AT&T and McCaw Cellular. AT&T, one of the largest U.S. corporations, was the dominant competitor in long-distance telephone communications in the United States. McCaw was the largest competitor in the rapidly growing cellular-telephone communications industry. Prior to the negotiations, AT&T had no position in cellular communications. This case and its companion (F-1143) are designed to allow students to be assigned roles to play. The case may pursue some or all of the following teaching objectives: exercising valuation skills, practicing strategic analysis, exercising bargaining skills, and illustrating practical aspects of mergers and acquisitions.
Details
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Communications regarding this column should be addressed to Mrs. Cheney, Peabody Library School, Nashville, Term. 37203. Mrs. Cheney does not sell the books listed here. They are…
Abstract
Communications regarding this column should be addressed to Mrs. Cheney, Peabody Library School, Nashville, Term. 37203. Mrs. Cheney does not sell the books listed here. They are available through normal trade sources. Mrs. Cheney, being a member of the editorial board of Pierian Press, will not review Pierian Press reference books in this column. Descriptions of Pierian Press reference books will be included elsewhere in this publication.
Wireless communication comprises telecommunications industry products and services which move voice, video, data, and graphics at the speed of the electron. But wireless is far…
Abstract
Wireless communication comprises telecommunications industry products and services which move voice, video, data, and graphics at the speed of the electron. But wireless is far more than products and services; it is the very backbone of the Internet. We have today a wireless world which two Chief ‘Ntrepreneur Officers (CNOs) – American Sam Ginn and Britisher Chris Gent – created during the 16 years between the Olympics in Los Angeles (1984) and Olympics in Sydney (2000).
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THE article which we publish from the pen of Mr. L. Stanley Jast is the first of many which we hope will come from his pen, now that he has release from regular library duties…
Abstract
THE article which we publish from the pen of Mr. L. Stanley Jast is the first of many which we hope will come from his pen, now that he has release from regular library duties. Anything that Mr. Jast has to say is said with originality even if the subject is not original; his quality has always been to give an independent and novel twist to almost everything he touches. We think our readers will find this to be so when he touches the important question of “The Library and Leisure.”
A tax based on land value is in many ways ideal, but many economists dismiss it by assuming it could not raise enough revenue. Standard sources of data omit much of the potential…
Abstract
Purpose
A tax based on land value is in many ways ideal, but many economists dismiss it by assuming it could not raise enough revenue. Standard sources of data omit much of the potential tax base, and undervalue what they do measure. The purpose of this paper is to present more comprehensive and accurate measures of land rents and values, and several modes of raising revenues from them besides the conventional property tax.
Design/methodology/approach
The paper identifies 16 elements of land's taxable capacity that received authorities either trivialize or omit. These 16 elements come in four groups.
Findings
In Group A, Elements 1‐4 correct for the downward bias in standard sources. In Group B, Elements 5‐10 broaden the concepts of land and rent beyond the conventional narrow perception, while Elements 11‐12 estimate rents to be gained by abating other kinds of taxes. In Group C, Elements 13‐14 explain how using the land tax, since it has no excess burden, uncaps feasible tax rates. In Group D, Elements 15‐16 define some moot possibilities that may warrant further exploration.
Originality/value
This paper shows how previous estimates of rent and land values have been narrowly limited to a fraction of the whole, thus giving a false impression that the tax capacity is low. The paper adds 14 elements to the traditional narrow “single tax” base, plus two moot elements advanced for future consideration. Any one of these 16 elements indicates a much higher land tax base than economists commonly recognize today. Taken together they are overwhelming, and cast an entirely new light on this subject.
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Anthony D. Songer and Karen R. Breitkreuz
Today’s higher education paradigm places emphasis on the broader context of globalization, economics, the environment, and society. Divergent from traditional silo-based…
Abstract
Today’s higher education paradigm places emphasis on the broader context of globalization, economics, the environment, and society. Divergent from traditional silo-based, discipline-specific models, this broad and complex challenge necessitates the continued investigation of innovative interdisciplinary approaches for higher education. The 360 Degree Model for Educating Socially Responsible Global Citizens developed by the authors (360 Global Ed model) addresses these current needs through a structured approach for developing students as global citizens through purposeful engagement (Breitkreuz & Songer, 2015; Songer & Breitkreuz, 2014).
The 360 Global Ed model includes a theoretical framework, educational environment, academic coursework, and evidence-based outcomes. At the core of the model is an international service learning (ISL) experience. The model’s ISL experience provides a collaborative, interdisciplinary classroom environment combined with an authentic international field experience (Songer & Breitkreuz, 2014).